EP1757426B1 - Process for producing a composite element comprising polyisocyanate-polyaddition products, in particular a hot water storage comprising polyurethane - Google Patents

Abstract

The method involves providing a container (1) and an outer casing (3) which holds the container, where the container has a base and a cover. The casing surrounds the container and forms a chamber (4) with the container. The isocyanates in the container are converted into reactive composites, in the chamber. The reaction mixture of an expanding agent and catalysts contain the auxiliary material and/or the additives.

Description

The invention relates to a method for producing a composite element comprising at least one compact component (i), rigid foam based on polyisocyanate addition products (ii) and at least one further compact component (iii), wherein at least one supporting, compact component (i) and providing at least one further compact component (iii), the further component (iii) being held by the supporting component, the further component (iii) surrounding the supporting component (i) and forming with it a space (iv) and in space (iv) reacting isocyanates with isocyanate-reactive compounds, wherein the reaction mixture further contains propellant and optionally catalysts, auxiliaries and / or additives, characterized in that the further compact component (iii) comprises a shell component (iii a), a bottom component ( iii b) and a ceiling component (iii c), which terminate to the shell component (iii a), and where in which the floor component (iii b) and the ceiling component (iii c) are each fastened to the supporting component (i) or the floor component, (iii b) and / or the ceiling component (iii c) by a component for reinforcement (v), which is arranged on the side facing away from the space (iv) of the bottom component (iii b) and / or the ceiling component (iii c) and is attached to the supporting component (i) are held.

Further embodiments of the present invention can be taken from the claims, the description and the examples. It is understood that the features mentioned above and those yet to be explained of the subject matter according to the invention can be used not only in the particular combination specified, but also in other combinations, without departing from the scope of the invention.

The use of rigid foams based on polyisocyanate polyaddition products, usually polyurethanes (PUR) and / or polyisocyanurates (PIR), as a material for thermal insulation is well known. Such foams are used for example in insulated pipes, sandwich panels, refrigerators and hot water tanks. The production z. As the hot water tank is generally characterized in that introduces the starting components for the production of foams with conventional processing machines in the space between the inner container and outer shell. By the subsequent foaming the cavity is completely filled.

By introducing a reaction mixture for the production of polyurethanes in a cavity, the mixture expands as a result of the formation of gas by the reaction. So there is an increase in volume of the reaction mixture. This is mainly dependent on the introduced amount of the reaction mixture.

A problem with foaming the gaps is that the volume of the reaction mixture in the last reaction phase slightly decreases and the foam shrinks. In order to counteract this decrease in volume, to completely fill the cavity and to produce a stable, non-shrinkable rigid polyurethane foam from the reaction mixture, it is necessary to fill a larger amount of the reaction mixture into the cavity to be foamed out and to overfill it. As a result, the reaction mixture is compressed and there is an increased pressure on the walls of the cavity, the so-called foaming pressure, which must withstand the object to be foamed. To withstand this pressure and counteract deformation, very expensive, temperature-controlled support forms are necessary. These support forms serve to maintain the original outer shape of the outer shell, referred to in this document as component (iii), and cost per piece about 10,000 to 300,000 €.

The production process with supporting forms is complicated because they have to be loaded and unloaded. In addition, a mold residence time is necessary, which depends on the curing of the reaction mixture. In order to be able to produce large numbers of pieces, several support forms are often necessary for a single product series. If the outer contours of the products to be foamed change, at the same time changes to the support tools are necessary, which is associated with very high costs. For smaller product quantities, the tool costs are a major factor in the overall costs, since the support tools for small series must be just as expensive to build, as in large quantities.

Composite elements that are manufactured without additional support form, i. without devices which ensure that the inner container and in particular the outer casing retain their shape due to the foaming, are designed to be self-supporting and can therefore withstand only a low foaming pressure. The term "self-supporting" is to be understood below that the corresponding elements do not lose their three-dimensional shape during foaming without additional support elements. In this case, the elements are referred to as load-bearing elements that absorb the force due to the foaming pressure (vi).

The prior art also discloses methods for producing such self-supporting composite elements. In this case, the outer container consists of jacket component and ceiling component wherein, during foaming, the ceiling component is secured to the shell component. Since such a construction is only slightly resistant to pressure, such a composite element is only possible by the use of special formulations which contain mostly halogenated hydrocarbons as blowing agents and special catalysts. These formulations are characterized by the fact that the foams produced therefrom shrink only slightly. Thus, when using these formulations only a small overfilling is necessary, which also results in only a low foaming pressure and expensive support forms are not needed. However, these formulations are expensive and not very environmentally friendly.

Another possibility for producing self-supporting composite elements without the use of external support forms is in EP 1 046 659 disclosed. To withstand the foaming pressure that occurs during foaming, the outer shell of the composite element is constructed as a pressure body, which can absorb the forces due to the foaming pressure. The bottom and lid are used with a curved shape. A composite element after EP 1 046 659 is usable up to a maximum pressure of 1.25 bar.

Starting from EP 1 046 659 however, it would be desirable to provide a composite member that is stable even at pressures greater than 1.25 bar to have greater flexibility in selecting possible blowing agents and catalysts.

The object of the invention was therefore a process for producing a self-supporting composite element, in particular a hot water tank, with a compact, supporting component (i), rigid foam based on polyisocyanate addition products (ii), which preferably contains no halogenated hydrocarbons as blowing agent, and at least to provide a further compact component (iii), which has a simple shape with as flat as possible floor to be used as a stand-up elements.

It was another object of the invention to provide self-supporting composite elements that are inexpensive to manufacture.

Finally, it was an object of the invention to provide such self-supporting composite elements, in the production of all conventional blowing agents can be used.

These objects could be achieved by the method described above for producing a composite element. The composite elements according to the invention can be present, for example, in configurations as a tube, sandwich element or preferably in the form of thermally insulated containers for liquids or gases, preferably liquids. For example, The composite elements may be contained in refrigerators or preferably in hot water tanks.

According to the invention, component (iii) is held by component (i). The term "held" is to be understood as meaning that the retained component retains its position within the composite component even when forces are applied. The acting forces are transferred to the holding component. This is especially true for forces generated during the reaction of isocyanates with isocyanate-reactive compounds. Component (iii) is attached to component (i), optionally via spacers, more preferably by screwing. Are the forces occurring forces that occur during the reaction of isocyanates with isocyanate-reactive compounds, holding component and supporting component are synonymous to understand.

Components (i) and (iii) represent the materials between which the rigid foam of component (ii), preferably adhering to (i) and (iii), is disposed. For example, (iii) may represent an outer skin or sheath, and (i) the inner component in which the material to be thermally insulated, e.g. the liquid or gas is located. In the case of designing the composite elements in hot water tanks, for example, (iii) represents the outer skin, while (i) forms the inner tank. This embodiment, in which (iii) represents an outer wall and (i) an inner container, and (ii) is arranged between (i) and (iii), represents a preferred embodiment.

The component (i), preferably the inner container of a hot water storage, can for example be based on conventional, preferably thermoplastic plastics, for example polystyrene, ABS, ASA, polypropylene, polyethylene, preferably metals, such as steel, aluminum and / or copper. Preference is given to (i), in particular in the embodiment as an inner container in hot water tanks, made of copper and / or steel, wherein the Surface may be enamelled if necessary. The thickness of (i) is preferably 1 to 4 mm

For component (iii), preferably the outer jacket of a hot water tank, well-known materials may be used, for example known plastics, e.g. Polystyrene, ABS, ASA, polypropylene, polyethylene or metals such as steel, aluminum and / or copper.

In a composite element produced by the method according to the invention, the further compact component (iii) comprises a shell component (iii a), a bottom component (iii b) and a ceiling component (iii c), wherein the bottom component (iii b) and the ceiling component (iii c) are each fastened to the supporting component (i) or, if a component for reinforcement (v) is used, are held by the latter and terminate in the jacket component (iii a). The shell component (iii a) is held by the bottom component (iii b) and the ceiling component (iii c). This holding of the sheath component (iii a) is preferably carried out by a protruding edge of the floor and ceiling component. Between the base or the ceiling component and the jacket component is preferably a sealing component, which prevents foam leakage.

The attachment of the bottom component (iii b) to the supporting component (i) preferably takes place via at least one spacer (vi). These are preferably attached to the load-bearing component (i) and to the floor component (iii b) and preferably carry the weight of the load-bearing component (i) and optionally the contents of the load-bearing component (i). Preferably, the spacer or spacers (vi) are bolted to the bottom component.

In a preferred embodiment, the ceiling component (iii c) is preferably fastened to at least one inlet or outlet (vii) of the supporting component (i), in particular by screwing.

Preferably, the bottom component (iii b) and the ceiling component (iii c) made of plastic, more preferably made of polystyrene, ABS, ASA, polypropylene or polyethylene.

It is also preferred that both the bottom component (iii b) and the ceiling component (iii c) are each substantially planar. Possible deviations from the plane can form attachment possibilities. Preferably, the sheath component (iii a), the bottom component (iii b) and the ceiling component (iii c) form a cylindrical body. In a particularly preferred embodiment, the composite element with the bottom component is placed on a further object.

In a particularly preferred embodiment, 3 or 4 spacers (vi) are used to attach the bottom component (iii b) to the supporting component (i). The heads of the screws for securing the spacers (vi) to the bottom component (iii b) preferably protrude beyond the bottom component. In a particularly preferred embodiment, the screws may be used in use of the self-supporting composite component, preferably when using the self-supporting component as a hot water tank, to ensure vertical alignment of the longitudinal axis of the composite element when parking the ground component on a surface.

During the reaction of the isocyanates with isocyanate-reactive compounds for component (ii), the soil component, the ceiling component or soil and the ceiling component in one embodiment further comprises a component for reinforcement (v). This reinforcing component (v) is arranged on the side of the bottom component (iii b) facing away from the space (iv) and / or the ceiling component (iii c) and likewise fastened to the supporting component. The attachment is preferably by screwing with the supporting component (i).

In one embodiment, the reinforcement component (v) may have any shape and size. In a further embodiment, however, this preferably does not extend beyond the shell component (iii a). Preferably, the component for reinforcement (v) is flat. The reinforcing component (v) may be made of any material, such as plastics or metals. The component for reinforcement (v) is preferably made of metal, in particular of steel.

The reinforcing component (v) may be removed from the composite component after foaming.

The component (ii) of the composite elements according to the invention preferably has a density of 0.02 to 0.10, more preferably 0.03 to 0.05 g / cm ³ . The reaction mixture for preparing component (ii) may comprise any propellant. Preferably, the reaction mixture for the preparation of component (ii) has no halogenated hydrocarbons. The reaction mixture for producing component (ii) particularly preferably has hydrocarbons, in particular pentane and isomers of pentane.

Preferably, the rigid foam (ii) of the components (i) and (iii), optionally with the exception of pipes in the interior of the hot water tank and for filling the space between (i) and (iii) with the starting components for the preparation of (ii) , enclosed. The thickness of (ii), i. the distance between (i) and (iii) is preferably between 5 and 150 mm.

A preferred embodiment of the invention is in FIG. 1 shown. The illustrated in this figure container, such as a hot water tank, recordable example, the actual container as the supporting component (i), and as a further compact component (iii) an outer shell, consisting of shell component (iii a), bottom component (iii b) and Ceiling component (iii c). The ceiling component (iii c) further comprises a component (v) for reinforcement. In this embodiment, the shell component (iii a) is held by a protruding edge of the bottom component (iii b) and the ceiling component (iii c). The pressure of the resulting foam, represented by the arrows (viii), is absorbed by the soil component (iii b) and the ceiling component (iii c) and derived to the supporting component (i).

In a particularly preferred embodiment of the invention, a composite element according to the invention is a thermally insulated container for liquids, in particular a hot water tank.

The reaction of isocyanates with isocyanate-reactive compounds in the presence of blowing agents and, if appropriate, catalysts, auxiliaries and / or additives to form the polyisocyanate polyaddition products which form component (ii) is well known and widely described.

The reaction for producing (ii) is preferably carried out such that the pressure (i) and / or (iii) produced during the foaming process is not deformed, i. in that the reaction mixture containing the isocyanates, the isocyanate-reactive compounds, the blowing agents and optionally the catalysts, auxiliaries and / or additives for the preparation of the rigid foam (ii) based on polyisocyanate polyaddition products in the reaction of 163 g of reaction mixture in a closed , cylindrical container with a volume of 4.08 I developed a maximum pressure in the container, which is less than 1.6 bar, preferably between 1.02 and 1.5 bar. In a further embodiment, the pressure is between 1.08 and 1.5 bar, in particular between 1.25 and 1.5 bar. The pressure generated during foaming can be measured by well-known methods.

Suitable isocyanates, preferably organic and / or modified organic polyisocyanates, are the aliphatic, cycloaliphatic, araliphatic and preferably aromatic polyfunctional isocyanates known per se, as used, for example, in US Pat EP-A 0 421 269 (Column 4, line 49, to column 6, line 22) or in EP-A 0 719 807 (Column 2, line 53, to column 4, line 21) are listed.

Diphenylmethane diisocyanate isomer mixtures or crude MDI having a diphenylmethane diisocyanate isomer content of from 33 to 55% by weight and urethane group-containing polyisocyanate mixtures based on diphenylmethane diisocyanate having an NCO content of from 15 to 33% by weight have proven particularly useful.

As isocyanate-reactive compounds, it is possible to use compounds having at least two isocyanate-reactive hydrogen atoms. For this purpose, compounds are suitable which carry two or more reactive groups selected from OH groups, SH groups, NH groups, NH ₂ groups and CH-acidic groups in the molecule.

Conveniently, those having a functionality of 2 to 8, preferably 2 to 6, and an average molecular weight of 60 to 8000 are used. Polyether polyamines and / or preferably polyols selected from the group consisting of polyether polyols, polyester polyols, polythioether polyols, polyester amides, hydroxyl-containing polyacetals and hydroxyl-containing aliphatic polycarbonates or mixtures of at least two of the mentioned polyols have proven successful, for example have an average molecular weight of 301 to 4000. Preferably used polyester polyols and / or polyether polyols. The hydroxyl number of the polyhydroxyl compounds is preferably 100 to 850, more preferably 200 to 600 mg KOH / g. Further details on the usable connections are for example EP-A-0 421 269 (Column 6, line 23, to column 10, line 5) or EP-A-0 719 807 (Column 4, line 23, to column 7, line 55). The rigid foams can be prepared without or with the concomitant use of chain extenders and / or crosslinking agents. To modify the mechanical properties, eg. As the hardness, however, the addition of chain extenders, crosslinking agents or optionally mixtures thereof may prove advantageous. As chain extenders and / or crosslinkers it is possible to use compounds having molecular weights of less than 400, preferably from 60 to 300, which usually have a functionality of from 2 to 6. Further details on these and other usable compounds are for example EP-A-0 421 269 (Col. 10, lines 6 to 48).

If chain extenders, crosslinking agents or mixtures thereof are used to prepare the rigid foams, these are expediently used in an amount of from 0 to 20% by weight, preferably from 2 to 8% by weight, based on the weight of the isocyanate-reactive compounds with one Molecular weight from 60 to 8000, used.

As blowing agent, all known blowing agents can be used. Conceivable are both chemical and physical blowing agents and mixtures thereof. Chemical blowing agents are compounds which form gaseous products by reaction with isocyanate. Physical blowing agents are understood as compounds which are dissolved or emulsified in the starting materials of polyurethane production and evaporate under the conditions of polyurethane formation. These are, for example, hydrocarbons, halogenated hydrocarbons, and other compounds, such as perfluorinated alkanes, such as perfluorohexane, chlorofluorocarbons, and ethers, esters, ketones and / or acetals. Preferably, the blowing agent used is water, pentane or isopentane, if appropriate in mixtures with one another or with further blowing agents.

As catalysts for the preparation of PUR and / or PUR / PIR rigid foams in particular compounds are used, the reaction of the reactive hydrogen atoms, especially hydroxyl-containing compounds of component (b) with the organic, optionally modified polyisocyanates (a) greatly accelerate. However, the isocyanate groups can also be reacted with one another by means of suitable catalysts, with isocyanurate structures preferably being formed in addition to the adducts between isocyanates and the compounds having hydrogen-active groups.

As catalysts, therefore, in particular those substances are used which accelerate reactions of the isocyanates, in particular urethane, urea and isocyanurate formation.

Preference is given to tertiary amines, tin and bismuth compounds, alkali metal and alkaline earth metal carboxylates, quaternary ammonium salts, s-hexahydrotriazines and tris (dialkylaminomethyl) phenols.

Further details on usable catalysts are for example EP-A-0 719 807 (Col. 9, lines 5 to 56).

The reaction mixture for the preparation of PUR and / or PUR / PIR rigid foams, if appropriate, can also be incorporated with auxiliaries and / or additives. Examples include surfactants, foam stabilizers, cell regulators, flame retardants, fillers, dyes, pigments, hydrolysis, fungistatic and bacteriostatic substances. Further details on the usable connections are for example EP-A-0 421 269 (Column 12, line 55, to column 14, line 16) or EP-A-0 719 807 (Column 9, line 58, to column 13, line 17).

To prepare the rigid polyurethane foams, the organic and / or modified organic polyisocyanates and the isocyanate-reactive compounds are reacted in amounts such that the equivalence ratio of NCO groups of the polyisocyanates to the sum of the reactive hydrogen atoms 0.85 to 1, 75: 1, preferably 1.0 to 1.3: 1 and in particular 1.1 to 1.2: 1, is. If the rigid foams contain at least partially bound isocyanurate groups, a ratio of NCO groups of the isocyanates to the sum of the reactive hydrogen atoms of the isocyanate-reactive compounds of from 1.5 to 60: 1, preferably 3 to 8: 1, is usually used.

The rigid foams are advantageously produced by the one-shot process, for example by means of high-pressure or low-pressure technology. It has proven to be particularly advantageous to work by the two-component process and to combine the isocyanate-reactive compounds, the blowing agents and optionally catalysts, auxiliaries and / or additives in component (A), the so-called polyol component, and as a component (B), the so-called isocyanate component, the isocyanates or mixtures of the isocyanates and optionally blowing agent to use.

The manufacture of sandwich panels, pipes or other articles of the invention is well known.

For example, the starting components are mixed at a temperature of 15 to 80 ° C, preferably from 18 to 25 ° C, and introduced into the space (iv), optionally under elevated pressure.

Advantages of the composite elements according to the invention are that they have substantially flat floor and ceiling elements and the composite elements can thus be used as stand elements. Another advantage of the composite elements according to the invention is that when changing the blowing agent component of halogenated hydrocarbons to environmentally friendly blowing agents no support tools must be used and, apart from minor changes to the bottom component (iii b) and the ceiling component (iii c), no redesign of the outer Sheath is required. Therefore, the production of the composite elements does not have to be changed.

Furthermore, fast model changes are possible due to the low demands on the mold. Due to the cost-effective production possibilities without high costs by necessary support tools or the special construction of an outer shell, which absorbs the forces of foaming pressure, it is possible to produce even small series cost or quickly change the production of different models.

Claims (6)

1. A process for producing a composite element comprising at least one compact component (i), rigid foam based on polyisocyanate addition products (ii) and at least one further compact component (iii), wherein
   at least one supporting, compact component (i) and at least one further compact component (iii) are made available and the further component (iii) surrounds the supporting component (i) and together with this forms a space (iv), and isocyanates are reacted with compounds which are reactive toward isocyanates in the space (iv), where the reaction mixture further comprises blowing agents and, if appropriate, catalysts, auxiliaries and/or additives,
   wherein the further compact component (iii) has a wall component (iii a), a bottom component (iii b) and a cover component (iii c), which end at the wall component (iii a), and with the bottom component (iii b) and the cover component (iii c) each being fastened to the supporting component (i) or the bottom component (iii b) and/or the cover component (iii c) being held by a component for reinforcement (v) which is arranged on the side of the bottom component (iii b) and/or of the cover component (iii c) facing away from the space (iv), and is fastened to the supporting component (i).
2. The process according to claim 1, wherein the bottom component (iii b) and the cover component (iii c) are each essentially flat.
3. The process according to claim 1 or 2, wherein (i) the wall component (iii a), the bottom component (iii b) and the cover component (iii c) form a cylindrical body.
4. The process according to any of claims 1 to 3,
   wherein the blowing agent is substantially pentane.
5. The process according to any of claims 1 to 4,
   wherein the composite element is a thermally insulated container for liquids.
6. A process according to claim 1, wherein the fastening between the supporting component (i) and the bottom component (iii b) and/or the supporting component (i) and the cover component (iii c) is released after production of the rigid foam.

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